Editorial: Types of methods research papers in the journal Campbell Systematic Reviews

Since its beginning in the early 2000s, the Campbell Collaboration has acknowledged the importance that methodology plays in producing systematic reviews. Indeed, the Methods Coordinating Group (CG) was one of the original groups in Campbell, alongside crime and justice, education, and social welfare. During the past two decades, numerous statisticians and methodologists have contributed to early forms of methods guidance and methods recommendations (it would be impossible to name them all and it would be unfair to just mention some). In recent years, with the expansion of the Campbell CGs, the type of questions asked and evidence used among CGs has diversified. These changes produce new challenges, and with new challenges new opportunities arise as well. In more recent years, with the intention to better serve the rest of the CGs, the Methods CG, with the support of the board, the Editor in Chief, and the CEO, started to produce discussion papers, methods guidance, and methods policy. These early efforts are collected as Methods Research Papers in the Campbell Systematic Reviews journal. Methods articles are open access, peer‐reviewed multidisciplinary manuscripts. The primary goal of the articles published within the Campbell Systematic Reviews journal is to provide methodological support for the systematic reviews and evidence and gap maps that it also publishes. As such, we welcome different categories of manuscripts (described more fully below):

Since its beginning in the early 2000s, the Campbell Collaboration has acknowledged the importance that methodology plays in producing systematic reviews. Indeed, the Methods Coordinating Group (CG) was one of the original groups in Campbell, alongside crime and justice, education, and social welfare. During the past two decades, numerous statisticians and methodologists have contributed to early forms of methods guidance and methods recommendations (it would be impossible to name them all and it would be unfair to just mention some). In recent years, with the expansion of the Campbell CGs, the type of questions asked and evidence used among CGs has diversified. These changes produce new challenges, and with new challenges new opportunities arise as well.
In more recent years, with the intention to better serve the rest of the CGs, the Methods CG, with the support of the board, the Editor in Chief, and the CEO, started to produce discussion papers, methods guidance, and methods policy. These early efforts are collected as Methods Research Papers in the Campbell Systematic Reviews journal.
Methods articles are open access, peer-reviewed multidisciplinary manuscripts. The primary goal of the articles published within the Campbell Systematic Reviews journal is to provide methodological support for the systematic reviews and evidence and gap maps that it also publishes.
As such, we welcome different categories of manuscripts (described more fully below): • Method: Innovative Methods Papers  Finally, the Methods CG will disseminate guidance and policy papers as Guidance and policy papers.

METHOD: INNOVATIVE METHODS PAPER
We welcome Innovative Methods Papers that introduce a novel approach to any of the stages of a systematic review, compare the use of different known methods, or demonstrate the accuracy or inaccuracy of a known method. Innovative Methods must be relevant to at least one of the stages of Campbell Systematic Reviews, or evidence and gap maps. These manuscripts must provide some examples (when feasible with real data), and the data and source code utilized in the example must be submitted at the time for the submission. If a simulation study is conducted, the source code of the simulation study must be included with the submission.
For an example of an Innovative Methods Paper see Polanin and Nuijten (2018).

RESEARCH METHODS GUIDE
There are papers that demonstrate, illustrate, and teach other researchers undertaking systematic review how to use specific methods. Whether focusing on a specific technique or software, these papers must be written in accessible language in order to reach a broader audience that may be interested in learning the practical use

METHOD: TRANSLATION
These are short (two to three pages) papers aimed at stakeholders and consumers of systematic reviews. These papers aim to communicate, in plain language, the reason that a particular method is used and why it matters for stakeholders and consumers. Translation

SYSTEMATIC REVIEWS OF METHODS
These are systematic reviews of methods. Systematic reviews of methods answer questions related, but not limited to: How is a particular method being used? What is reported when a particular method is being used? What is the overall bias or precision of a method while synthesizing multiple simulation studies? For examples of Systematic Reviews of Methods see Villar and Waddington (2019) and Wang et al. (2021).

GUIDANCE PAPERS
The Methods CG encourages the constituents of the Campbell Collaboration to write guidance papers. Guidance Papers are recommendations in how to approach a particular issue. Although it may be considered good practice to follow a specific guidance, it is not mandated or expected that all Campbell reviews comply with these. Guidance papers are sent for consultation with all CGs as part of the peer review process. The guidance on information retrieval (Kugley et al., 2017) and on evidence and gap maps (White et al., 2020) are examples of guidance.

POLICY PAPERS
Policies are, typically, previous guidance that has been elevated to policy. All Campbell reviews are expected to comply with policies. As part of the peer review process, Policy Papers are sent for consultation to all CGs. In addition, policies need to be approved by a